Presented by Gene Vogel
EASA Pump & Vibration Specialist

The repair of roto-dynamic pumps (pumps with centrifugal and axial flow impellers) requires that, as much as possible, the mechanical condition of the pump be returned to factory specifications. This presentation focusses on critical close fit tolerances and certain surface finish specifications. The best recommendation is always that factory tolerances be used. However, when those factory tolerances are simply not available and the pump must be repaired, service centers rely on general rules of thumb and experience to complete repairs. 

The following concerns will be reviewed: 

• Rolling element bearings 
• Sleeve bearings (horizontal) 
• VTP bearings 
• Impeller-casing wear rings 
• Casing rabbets 
• VTP motor mounting flange runout and P-flange type motor bases 
• Throttle (throat) bushings 
• Impeller-shaft fit 
• Stage bushings 

This summary of data, collected from various service centers, pump manufacturers, parts manufacturers and engineering resources, assembled in one resource, will be helpful to pump repair technicians, supervisors and engineers.